1. Technical Field
The present disclosure relates to an operational amplification circuit having a differential amplification circuit portion which uses a current mirror circuit.
2. Related Art
FIG. 4 is a diagram illustrating an example of an operational amplification circuit having a current mirror circuit in the related art. The operational amplification circuit is provided with a differential amplification circuit portion 1 in which a pair of MOS transistors T20 and T21 are differentially connected, a current mirror circuit portion 2, a constant current circuit portion 3, and an output circuit portion 4. The output circuit portion 4 is formed of a MOS transistor T22 and a load resistor 5 connected to a drain output terminal of the MOS transistor T22. A gate of the MOS transistor T22 is connected to a drain output terminal of the MOS transistor T20.
In the operational amplification circuit configured as described above, a differential amplification output of the drain of the MOS transistor T20 of the differential amplification circuit portion 1 is applied to the gate of the MOS transistor T22 of the output circuit portion 4, and an electric current corresponding to a gate voltage of the MOS transistor T22 flows in between the source and the drain of the MOS transistor T22, thereby outputting an output voltage VOUT.
Examples of the related art are disclosed, for example, in Japanese Unexamined Patent Application Publication No. 5-63455 and Japanese Unexamined Patent Application Publication No. 11-127037.